c-generator: add the module tag back into attr and bindslot defines.

[floooh]

This is a regression fix for #160

E.g. with @module bla the attribute and bindslots constants now look like this:

• ATTR_prog_pos => ATTR_bla_prog_pos
• IMG_tex => IMG_bla_tex
• SMP_smp => SMP_bla_smp
• UB_vsparams => UB_bla_vsparams
• SBUF_ssbo => SBUF_bla_ssbo